1self.addEventListener('install', function(e) {
 2    e.waitUntil(
 3        caches.open('daily-kanji').then(function(cache) {
 4            return cache.addAll([
 5                '/daily-kanji/',
 6                '/daily-kanji/index.html',
 7                '/daily-kanji/main.js',
 8                '/daily-kanji/style.css'
 9            ]);
10        })
11    );
12});
13
14self.addEventListener('fetch', function(event) {
15    event.respondWith(
16        caches.match(event.request).then(function(response) {
17            return response || fetch(event.request);
18        })
19    );
20});